Historical demography of Trichothraupis melanops (Aves: Thraupidae) and the Pleistocene Atlantic Forest biogeography

Abstract

The climatic cycles of the Pleistocene affected the distribution of the vegetation of different biomes, determining the distribution and evolution of the associated fauna. Many studies of Atlantic Forest (AF) organisms suggest that the Pleistocene glacial and interglacial cycles have produced demographically stable populations in the forest’s central region and unstable populations in its southern regions (known as the Carnaval-Moritz model). We studied the phylogeographic structure of an AF passerine, the Black-goggled Tanager (Trichothraupis melanops, Thraupidae) and evaluated questions related to the history of the AF. We analyzed three independent genes, two nuclear and one mitochondrial, using population genetic methods based on summary statistics and traditional phylogeographic methods. Our results suggest that T. melanops shares phylogeographic features with other AF taxa. Even though an effective population size gradient was found between the central and southern populations, which is in agreement with the results of other phylogeographic studies and the forest refugia model (the Carnaval-Moritz model), there is no evidence of a gradient of genetic diversity. In addition, we have found that T. melanops populations show the demographic dynamics expected according to the Carnaval-Moritz model: the inland-southern population was found to be the one with the greatest signs of recent demographic expansion, compared to the central and coastal-southern populations. Although this species is ecologically generalist and not very sensitive to forest fragmentation and degradation, it has been impacted by the historical dynamism of the AF.